The summit of Mount Everest is 8848 m above sea level. The atmospheric pressure, and the partial pressure of oxygen at the summit, are about one third of that at sea level. Altitudes above 8000 m are called the death zone for the reason that the human body is thought to be incapable of acclimatizing to such low partial oxygen pressures. The body begins to shut down causing the loss of vital functions. An indirect cause of death is the physical and mental stress causing climbers to make fatal mistakes.
